Methods for hydraulic fracturing and wellbore startup

Abstract

Properties of reservoir rock, hydraulic fracturing materials and a wellbore to be stimulated are determined. One or more preliminary designs for hydraulic fracturing and well production is selected. The data and designs are entered into one or more computer models for calculating well productivity after the hydraulic fracturing treatment. A treatment and well startup design is selected that will provide maximum well productivity, and work proceeds accordingly.

1 . A method for hydraulic fracturing and wellbore startup, comprising:
 a. determining properties of a reservoir, hydraulic fracturing materials and a wellbore to be stimulated;   b. selecting one or more preliminary designs for a hydraulic fracturing treatment and initiation of well production, wherein the selection of the one or more preliminary designs comprises selection of a maximal pressure drop between the reservoir and the wellbore during the wellbore startup and production;   c. entering data from stages (a) and (b) into one or more computer models for calculating well productivity after the hydraulic fracturing treatment;   d. selecting a treatment design and a well startup design;   e. performing a hydraulic fracturing treatment according to the design of stage (d); and   f. initiating well startup and production.   
     
     
         2 . The method of  claim 1 , wherein the one or more computer models comprise hydraulic fracturing, fracture conductivity and well production models. 
     
     
         3 . The method of  claim 2 , wherein the one or more computer models comprise PKN, KGD, Radial, Pseudo 3D, Planar 3D, Full 3D or UFM or combinations thereof. 
     
     
         4 . The method of  claim 2 , wherein the fracture conductivity model accounts for a pressure-drop effect between the reservoir and the wellbore as the fracture conductivity decreases. 
     
     
         5 . The method of  claim 2 , wherein the fracture conductivity model accounts for proppant flowback during well production. 
     
     
         6 . The method of  claim 2 , wherein the well production model accounts for heterogeneous distribution of fracture conductivity evolving with time. 
     
     
         7 . The method of  claim 2 , wherein the well production model calculates a wellbore productivity index. 
     
     
         8 . The method of  claim 2 , wherein the well production model calculates an equivalent fracture conductivity constant for which the well production is the same as that for heterogeneous conductivity distribution. 
     
     
         9 . The method of  claim 1 , wherein the selection of the one or more preliminary designs comprises selection of concentrations and volumes of the hydraulic fracturing materials, and pumping rate. 
     
     
         10 . (canceled) 
     
     
         11 . The method of  claim 1 , wherein the selection of the one or more preliminary designs comprises pulsing injection of the hydraulic fracturing materials. 
     
     
         12 . The method of  claim 1 , wherein the treatment design is selected to maximize well productivity. 
     
     
         13 . The method of  claim 1 , wherein a maximal pressure drop between the reservoir and the wellbore is selected to maximize well productivity. 
     
     
         14 . The method of  claim 1 , wherein the hydraulic fracturing materials comprise fluids, proppants and additives. 
     
     
         15 . The method of  claim 14 , wherein the additives comprise fibers, fluid-loss additives, diverting agents, breakers, corrosion inhibitors, friction reducers, scale inhibitors, surfactants, water soluble polymers, oil-soluble polymers, crosslinkers, biocides, pH adjusting agents or buffers, or combinations thereof.